This invention relates to a composite slide member which exhibits an excellent anti-seizing property under the condition of a boundary lubrication (which means a lubricating condition in which solid contact occurs on projections on a sliding surface, so that wear and seizing are liable to occur) and under the condition of starved lubrication (which means a condition in which solid contact occurs because of an oil shortage, so that wear determines the lifetime).
Conventional slide members used under a boundary lubrication condition and a starved lubrication condition comprise a metal back, a porous metal layer sintered on a surface of the metal back, and an impregnation coating layer which is impregnated into the porous metal layer and is coated on the surface of this porous metal layer. Examples of such an impregnation coating layer composition mixture include polytetrafluoroethylene (hereinafter referred to as "PTFE")-20 vol. % Pb, PTFE-20 vol. % Pb with a large specific surface area, PTFE-10 vol. % tetrafluoroethylen.perfluoroalkyl vinyl ether copolymer (hereinafter referred to as "PFA")-20 vol. % Pb with a large specific surface area.
As disclosed in Japanese Patent Unexamined Publication No. 59-19128, in order to avoid the possibility that the surface layer of such a composite slide member is removed at an initial stage of the operation with the result that a bearing clearance becomes large, machining is beforehand applied to the sliding surface to scatteredly expose both of the porous metal layer and the impregnation coating layer at the sliding surface, and then the composite slide member is used.
In the above prior art, however, when the amount of cutting allowance from the surface of the composite slide member is increased during the machining of this surface, the porous metal layer becomes much exposed abruptly, which has resulted in a problem that the composite slide member becomes seized to its mating shaft under the boundary lubrication condition and/or the starved lubrication condition.